<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title>dog</title>
    <script>
        function Dog(name, breed, weight) {
            this.name = name;
            this.breed = breed;
            this.weight = weight;
        }
        Dog.prototype.species = "Canine";

        Dog.prototype.bark = function() {
            if (this.weight > 25) {
                console.log(this.name + " says Woof!");
            } else {
                console.log(this.name + " says Yip!");
            }
        };
        Dog.prototype.run = function() {
            console.log("Run!");
        };
        Dog.prototype.wag = function() {
            console.log("Wag!");
        };

        var fido = new Dog("Fido", "Mixed", 38);
        var fluffy = new Dog("Fluffy", "Poodle", 30);
        var spot = new Dog("Spot", "Chihuahua", 10);
        spot.bark = function() {
            console.log(this.name + " says WOOF!");
        };

        fido.bark();
        fido.run();
        fido.wag();

        fluffy.bark();
        fluffy.run();
        fluffy.wag();

        spot.bark();
        spot.run();
        spot.wag();
    </script>
</head>
<body>
    
</body>
</html>